A polymeric solid electrolyte is a kind of polymeric thin film performing ion conduction rather than electron conduction. The polymeric solid electrolyte is adapted to be used in a series of primary and secondary lithium cells or lithium-ion cells to thin the cells in shape. The thinned cells also can be further processed into windable cells, bipolar stack cells, thin-film cells, etc., according to various requirements. In addition, the use of polymeric solid electrolytes in the cells can overcome the problems of difficult package and current leakage encountered by general cells with liquid electrolyte.
In earlier stage, the research on polymeric solid electrolytes is focused on the polyethylene oxide-based material. The material has a relatively low conductivity, as low as 10.sup.-7 .about.10.sup.-8 S/cm, at room temperature so that the material works only at high temperature such as 80.degree. C. or above. Furthermore, a lot of organic solvent which is detrimental to the industrial security and the environmental protection is used and then evaporated in the process for producing the polyethylene oxide-based thin film.
In recent years, gel electrolytes have been reported to be used in cells, and the product has a practically desired level of conductivity at room temperature. Nevertheless, the film has to be produced in a glove box or dry room so that the manufacturing process will be built with high cost.